Valencia have gone from being the laughing stock of La Liga a year ago to becoming the main challengers to Barcelona in the title race and face the biggest test of their credentials when they host Ernesto Valverde's leaders on Sunday.
Valencia, the six times Liga champions who last lifted the title in 2004 under Rafael Benitez, are on a club record run of eight straight wins and another victory in Sunday's top-of-the-table clash would put them within a point of Barcelona.
But the Catalans, who have won 11 of their 12 games so far, meanwhile, would take an almighty step to reclaiming the title even at this early stage if they win at The Mestalla, with usual challengers Real Madrid and Atletico Madrid 10 points adrift.
Valencia have hurtled from one crisis to the next over the last five years, appointing 10 coaches since parting ways with Unai Emery in 2012, but they have finally found a suitable man for the job in Marcelino.
The Spaniard, who turned his previous club Villarreal from a recently relegated side into a regular fixture in European football, inherited a team that came 12th two years in a row and who last season conceded the most goals in the club's history.
Valencia had a huge clear out in the close season, getting rid of 13 players and replacing them with high-profile loan signings such as Geoffrey Kondogbia, Goncalo Guedes, Jeison Murillo and Andreas Pereira.
As well as getting the best out of those signings, Marcelino has helped revive the likes of captain Dani Parejo, often criticised for his inconsistency, and Simone Zaza, a flop at West Ham United who has struck nine goals this season and only trails Barca's Lionel Messi in the Liga scoring charts.
Barnstorming Valencia have blown opponents away this season, thumping Real Betis 6-3, Malaga 5-0 and Sevilla 4-0.
They have also learned the art of earning scrappy, barely deserved wins, such as last Sunday's 2-0 victory at Espanyol, a game striker Santi Mina said showed Valencia had what it takes to compete with Barcelona for the title.
Marcelino will be absent from the dugout on Sunday due to a touchline ban after being sent off against Espanyol, although defender Martin Montoya says the screaming voices of 55,000 supporters at The Mestalla will motivate his side.
"Mestalla will be a cauldron of noise and the fans can give us a real lift towards the victory we are hoping for," Montoya told the club's official radio station.
"We cannot wait for Sunday's game and if we can sink our teeth into Barca, all the better."
Valverde rested Messi for the first time this season in Wednesday's 0-0 Champions League draw at Juventus in preparation for Sunday's showdown, though he is short in central defence with Gerard Pique suspended and Javier Mascherano injured.
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